Bidirectional file sync over SSH.
Zero remote dependencies. Native .gitignore. Content-addressed.

nix run github:andrewgazelka/zsync -- user@server

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Tired of:

• rsync re-uploading entire files for tiny changes
• mutagen requiring a 50MB daemon and complex setup
• scp having no idea what .gitignore is

zsync fixes this. Your remote server needs nothing installed — a 3MB agent auto-deploys via SSH.

Install

# Nix (recommended)
nix run github:andrewgazelka/zsync

# Cargo
cargo install --git https://github.com/andrewgazelka/zsync

Usage

# Sync current directory to remote (auto-creates ~/zsync/<dir_name>)
zsync root@server

# Custom SSH port
zsync root@server -p 22222
zsync root@server:22222           # same thing

# Explicit remote path
zsync root@server:/workspace/project

# Watch mode — bidirectional sync as you edit locally or remotely
zsync root@server --watch

# Delete remote files not present locally
zsync root@server --delete

Why zsync?

	rsync	mutagen	zsync
Only sends changed bytes	❌ Often whole file	❌ Often whole file	✅ FastCDC chunks
Cross-file dedup	❌	❌	✅ Content-addressed
Zero remote setup	❌ Must install	✅ Auto-deploy	✅ Auto-deploy
Agent size	N/A	~50MB	~3MB
Native .gitignore	❌ Manual flags	❌ Partial	✅ Full support
Bidirectional sync	❌	✅	✅ Built-in
Watch mode	❌ External tools	✅ Built-in	✅ Built-in
Port forwarding	❌	❌	✅ Built-in

How It Works

zsync uses content-addressed storage with FastCDC chunking. Files are split into variable-size chunks based on content, not position. Each chunk is identified by its BLAKE3 hash.

sequenceDiagram
    participant Local
    participant Remote

    Local->>Remote: SSH connect, auto-deploy 3MB agent
    Local->>Remote: What files do you have? (BLAKE3 hashes)
    Remote-->>Local: Here's my manifest
    Local->>Local: Diff, chunk changed files with FastCDC
    Local->>Remote: Which chunks are you missing?
    Remote-->>Local: Just these 3 chunks
    Local->>Remote: Here they are (deduplicated)
    Remote->>Remote: Reassemble files from chunks

Loading

Result: If you change one line in a 10MB file, only ~4KB transfers. Sync multiple similar projects and shared code chunks are never re-sent.

Configuration

Optional .zsync.toml in your project:

# Include files even if gitignored
include = [".env", "config/*.local"]

# Port forwarding (active in watch mode)
[[forward]]
local = 8080
remote = 8080

[[forward]]
local = 5432
remote = 5432

Platforms

Local: macOS (Apple Silicon, Intel), Linux Remote: Any Linux server with SSH

Status

Production-ready with bidirectional sync in watch mode.

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MIT OR Apache-2.0